Generally, if you can "feel" the scratch with your fingernail, you often can't just "buff it out." You can sand it out with wetordry paper, then rub the area with a rubbing or mild cutting compound, then finish with a polish (NOT wax). If you've never sanded out scratches before, start with a very fine grit -- I'd even recommend as high as 1000 -- it'll take a little longer, but you'll be far less likely to get carried away and go through the finish. Check your progress often.
If when running your fingernail over the scratch you DON'T feel it, you can usually skip the sanding, start right in with the rubbing compound and follow with polish.
Good luck!